Flood

In Commander, Flood competes against hard removal, bounce, and tap effects that don't require a recurring mana tax — it rarely makes the cut when one blue mana each upkeep could instead go toward anything else. Legacy and Vintage have access to it, but neither format has ever wanted it; the effect is too slow and too narrow next to counterspells and actual stax pieces. Pauper is the one space where Flood has occasionally appeared in prison or control shells as a way to strand a key threat, though even there it's fringe. Oathbreaker inherits Commander's card-pool depth, so the same logic applies.